The four-time Pro Bowler, who has not played since suffering a concussion and seizure Oct. 23, has been placed on injured reserve.

Earlier on Wednesday, the Chargers continued to try to bolster their offensive line, signing guard/tackle Ike Ndukwe.

The veteran free agent most recently spent the preseason with the New York Giants. He last played in 2009 for the Kansas City Chiefs. He started 15 games for the Miami Dolphins in 2008.

The Chargers signed Tony Moll, also a swing lineman, on Tuesday.

The team could be down as many as three starters this Sunday in Chicago. In their most recent game, the Chargers were down to their last lineman and even had to insert rookie tackle Stephen Schilling for one snap at right guard.

In addition to Dielman, right guard Louis Vasquez sprained his ankle against the Oakland Raiders last week. And left tackle Marcus McNeill suffered a neck stinger against Oakland, the second time in four games he has has to leave due to a neck injury.

Dielman suffered a concussion with just under 12½ minutes remaining yet stayed in the game. He was diagnosed with a concussion after the game and suffered a gran mal seizure as the team plane descended into San Diego. He was taken to the hospital and released the next day.

Initially expected to have a chance to play after two weeks off, he is still experiencing symptoms that made him unable to play.